Reaction

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reaction

1. opposition to change, esp political change, or a desire to return to a former condition or system
2. a response indicating a person's feelings or emotional attitude
3. Med
a. any effect produced by the action of a drug, esp an adverse effect
b. any effect produced by a substance (allergen) to which a person is allergic the simultaneous equal and opposite force that acts on a body whenever it exerts a force on another body

Reaction

 

in the political sense, resistance to social progress; a political regime established to maintain and strengthen an outmoded social order. Reaction usually manifests itself in the struggle against the revolutionary movement, in the suppression of democratic rights and liberties, in the persecution of progressive political, public, and cultural figures, in mass terror and violence, in racial and national discrimination, and in an aggressive foreign policy. Reaction in its extreme form is fascism.

A reactionary is an adherent of political reaction, a retrograde person, an enemy of social, cultural, and scientific progress.


Reaction

 

in psychology, a behavioral act that takes place in response to a certain stimulus; a voluntary movement that takes place in response to a signal and is influenced by the subject’s idea of the task to be performed. It became necessary to investigate voluntary reaction after it was discovered that astronomers attempting to note the moment a star passed through a meridian were giving different figures. F. Bessel, who discovered this phenomenon, conducted an experiment in 1823 to measure reaction times of human beings to stimuli. The measurement of speed, intensity, and course of reactions created psychometrics as a branch of psychology with a special method of investigation—the method of reaction. Pioneers in this field included F. Donders of Denmark and W. Wundt, L. Lange, and N. N. Lange. Reaction was also studied by the Soviet psychologist K. N. Kornilov, the founder of reactology.

There are two basic types of reactions: simple and complex. In a simple reaction, a person quickly responds with a movement (motor and sensory reaction) to a single prearranged signal. In a complex reaction, when various signals are randomly given, a person responds to only one of them (discrimination reaction) or to all of them, but with various movements (choice reaction). The study of reaction has made it possible to formulate a number of principles of applied psychology, such as Hick’s law, which states that reaction time increases with an increase in the number of stimuli presented for discrimination.

REFERENCES

Wundt, W. Osnovy fiziologicheskoi psikhologii, fascs. 1–16. St. Petersburg, 1908–14.
Inzhenernaia psikhologiia za rubezhom. Moscow, 1967. Pages 408–24. (Collection of articles translated from English.)
See also references under .

V. I. MAKSIMENKO

reaction

[rē′ak·shən]
(control systems)
(mechanics)
The equal and opposite force which results when a force is exerted on a body, according to Newton's third law of motion.
(nuclear physics)
References in periodicals archive ?
Biopsies of reactional patients were collected either at diagnosis, during or after the course of multidrug therapy (MDT); however, none of the patients had received any corticosteroids or thalidomide to treat the reactional event.
The developmental systems approach posits that all behavior has a developmental history, a principle embodied in Kantor's idea of the reactional biography.
Without necessarily agreeing with this position concerning both Christians and Islamists, the idea that the radical, fanatical expression of Islamism may be circumstantial -- because it is reactional -- is defended by many, including numerous Islamists.
Heat of passion law originally categorized human reactional behavior in provocation situations, and there is no reason why, in a modern society comprising varying moral standards, the law cannot step in and articulate socially acceptable conduct.
Perhaps the major question in this entire issue is: why do educators use personally reactional decision-making so extensively?
If the evidence continues to mount, the question arises as to whether there are predictive models that might suggest the reactional behavior of abortion providers.
It is, in so far as its relevance to art is concerned, further evidence about the links with science that this reactional movement led to, but the connection between art and science as a matter of urgent debate is now more historically interesting than relevant to contemporary practice.
Morphological assessment can also indicate leprosy neuropathy, while colour Doppler imaging can help in associated reactional states.
Hansen's disease is a chronic disease and the course can be further complicated with reactional states and disabilities, which may require admission thereby affecting the working capacity of the individual.
If this is your problem, you may be suffering from an abnormal increased appetite for consumption of food known as reactional hyperphagia.
Reactional states of leprosy are expressions of immunological disturbance and are generally divided into two variants: type 1 (Jopling's type I or reversal reaction) and type 2 (Jopling's type II reaction), which relates to erythema nodosum leprosum (ENL) (1).
Effect of GaAIAs laser on reactional dentinogenesis induction in human teeth.